This invention relates to improved electrochemical devices of the type comprising an anode, a cathode, and an electrolyte in combination with support and/or coolant plates. More particularly, this invention relates to an electrochemical device utilizing a relatively low cost, lightweight support or coolant plate comprising a polymer/metal composite such as polysulfone/nickel. For convenience hereinafter, the invention will be described with reference to a fuel cell for the direct generation of electricity utilizing two non-consumable electrodes. As will be apparent, however, similar considerations governing the use of the invention in fuel cells will apply to other electrochemical devices enabling the use of the invention in such devices.
A fuel cell, as the term is employed herein, designates an electrochemical cell for the direct generation of electrical energy from a fuel and oxidant. With such cells, it is not necessary to go through the usual conversion of chemical energy to heat energy to mechanical energy to electrical energy as is common with heat engines. Such cells in their most simplified design comprise a housing, an oxidant electrode, a fuel electrode, an electrolyte, and means for feeding the fuel and oxidant to the respective electrodes. In operation, it is necessary that the fuel and oxidant contact a surface of their respective electrodes where a process of adsorption and desorption occurs leaving the electrodes electrically charged, with the second surface of the electrodes being in contact with the electrolyte. Depending upon the nature of the electrolyte, ions are transferred through the electrolyte from the anode to cathode, or from the cathode to the anode. Electrical current is withdrawn from the cell and passed through a suitable load where work is accomplished.
A problem associated with fuel cells is in the accommodation of reaction by-products formed during the operation of the cell. In the case where hydrogen is the fuel and oxygen is the oxidant, the by-product formed is water. An additional problem associated with such cells is heat transfer, i.e., supply of heat during start-up, and control of heat during operation of the cell. Accordingly, support and/or coolant plates are constructed and arranged with the cells to facilitate by-product (water) removal, distribution of reactant gases, and to remove and/or supply heat to the cell, or battery of cells. These plates must be light in weight, have good thermal conductivity, low electrical resistance, low thermal expansion, low shrinkage, and generally good structural stability. In view of the aforesaid requirements, polymer plates, although suggested for such use, are not completely acceptable in view of the low thermal conductivity and their electrical non-conductivity or resistivity. Metal plates are not completely acceptable in view of their high cost and susceptibility to corrosion.